Abstract: This paper proposes a novel dynamic octree structure to overcome the difficulty of the machinable workpiece modeling that virtual manufacturing is facing.First,The elementary geometry unit constructed with projected planes,which is used to construct the dynamic octree structure,is represented.Second,the self-similitude recursion algorithm is represented to realize a dynamic model with variable levels of detail,namely,there is a higher level of detail where is closer to the part of being machined.Finally,a model of machinable workpiece integrated into a virtual manufacturing environment is constructed,which is coded in C⁺⁺ Builder and OpenGL.